This invention is in the field of plastic injection molding machines and more particularly relates to an apparatus for transposing the plasticizing unit from or to a position in which, withdrawn from the injection molding unit, it rests on a support in an orientation approximately coaxially with the injection axis, to or from an emplacement situated at the rear side of the injection molding machine. The injection molding machine has at least one hydraulic power cylinder assembly for axially displacing the injection molding unit--including the plasticizing unit--from an injection position in which it injects synthetic material into the injection mold assembly, into a disengaged position in which the plasticizing unit is withdrawn and thermally separated from the injection mold assembly and in which the longitudinal axis of the plasticizing unit is still substantially coaxial with the injection axis.
The transposing apparatus has at least one stationary transport rail oriented transversely to the injection axis, a sled mounted for travel on the transport rail and a hoisting device mounted on the sled and arranged for lifting the plasticizing unit to a transporting height. The hoisting device has a sled-side coupling arrangement which is complemental and cooperates with a cylinder-side coupling arrangement of the plasticizing unit.
In a transposing apparatus of the above-outlined type, as disclosed, for example, in European Pat. No. 69,221, a frame construction mounted on the ceiling of the plant room extends over the injection molding machines as well as a storage magazine for the plasticizing units. The frame construction supports a gantry which is movable transversely to the injection axis of the injection molding machines and which has a trolley movable relative to the gantry parallel to the injection axis. The trolley has a vertically movable carrier arm with coupling organs. When a plasticizing unit is to be replaced, first its connections with the injection molding unit are uncoupled. Thereafter the plasticizing unit is grasped with the coupling organs of the trolley, conveyed to the storage magazine and deposited therein. Subsequently, the carrier arm grasps the new plasticizing unit and, after conveyance in the opposite direction, deposits the plasticizing unit into the respective injection molding machine. During the transport from the injection molding machines to the storage magazine, the plasticizing units are suspended from the carrier arm of the trolley and necessarily travel in an elevated transporting position above the areas occupied by operating personnel at the service side of the injection molding machines.